Muscular System Overview PDF

MUSCULAR SYSTEM OVERVIEW  THE MUSCLES The muscular system is a complex network of tissues responsible for movement, stability, generating heat, and various bodily functions. It is made up of fibers that contract when stimulated by nerve impulses.  KEY FUNCTION OF MUSCLE TISSUE Movement - Mus...

MUSCULAR SYSTEM OVERVIEW  THE MUSCLES The muscular system is a complex network of tissues responsible for movement, stability, generating heat, and various bodily functions. It is made up of fibers that contract when stimulated by nerve impulses.  KEY FUNCTION OF MUSCLE TISSUE Movement - Muscles are the primary agents of motion, enabling us to walk, run, jump, and perform other physical activities.  KEY FUNCTION OF MUSCLE TISSUE Posture Maintenance: Muscles work together to hold the body in an upright position and maintain balance. KEY FUNCTION OF MUSCLE TISSUE Heat Generation: Muscle contractions produce heat, which helps to regulate body temperature.  KEY FUNCTION OF MUSCLE TISSUE Organ Function: Muscles are involved in the movement of substances within organs, such as the heart, stomach, and intestines.  INVERTEBRATES VS. VERTEBRATES MUSCLE SYSTEM Feature Invertebrates Vertebrates More complex, Muscle structure Simpler, often in bundles organized into groups Muscle types Variety, including hydrostatic, circular, Skeletal, cardiac, and longitudinal, adductor, and abductor smooth Movement Diverse, including crawling, Eficient and swimming, flying, and burrowing coordinated mechanisms  INVERTEBRATES MUSCLE SYSTEM Invertebrates often possess simpler structures than vertebrates in terms of muscle systems. They frequently rely on bundles of muscle fibers, which are groups of individual muscle cells that work together. These bundles can be arranged in various ways, depending on the specific needs of the invertebrate.  INVERTEBRATES MUSCLE SYSTEM Invertebrates exhibit a remarkable diversity of muscle types, each adapted to perform specific functions. Hydrostatic Muscles Circular and Longitudinal Muscles Adductor and Abductor Muscles INVERTEBRATES MUSCLE SYSTEM Hydrostatic muscles are found in invertebrates with fluid-filled body cavities, such as earthworms, jellyfish, and sea anemones. They function by manipulating the pressure and shape of the fluid within the body to generate motion. INVERTEBRATES MUSCLE SYSTEM Hydrostatic Muscles Earthworm, the coelomic fluid (fluid in the body cavity) acts as a hydrostatic skeleton. The worm's muscles push against this fluid, allowing it to change shape and move efficiently. INVERTEBRATES MUSCLE SYSTEM Circular and Longitudinal Muscles These muscles are arranged in circular and longitudinal patterns around the body of invertebrates, such as worms. INVERTEBRATES MUSCLE SYSTEM Circular muscles wrap around the body in a ring-like manner. When they contract, the body or segment narrows or elongated. Circular muscles work by decreasing the diameter of the body or tube-like structure. INVERTEBRATES MUSCLE SYSTEM Longitudinal muscles run lengthwise along the body segments. When they contract, the body shortens and widens. Longitudinal muscles oppose the action of circular muscles. INVERTEBRATES MUSCLE SYSTEM Adductor and Abductor Muscles Adductor muscles bring body parts closer together, while abductor muscles move them apart. These muscles are essential for defense, flexibility, and precision in movements. INVERTEBRATES MUSCLE SYSTEM Adductor and Abductor Muscles Bivalve Mollusks (oysters, clams): Adductor muscles: pulling the two shells (valves) together Crustaceans (crabs): Adductor muscles: controlling the closing of claws (chelae). Abductor muscles: controlling the limbs and appendage movements.  INVERTEBRATES MUSCLE SYSTEM Diverse Movement Mechanisms Invertebrates have evolved a wide range of movement mechanisms, allowing them to adapt to various environments. Crawling Swimming Flying Burrowing INVERTEBRATES MUSCLE SYSTEM Crawling: Many invertebrates, such as worms and insects, crawl using their muscles to create waves of movement. Swimming: Aquatic invertebrates, such as jellyfish and fish, use their muscles to propel themselves through the water. Flying: Insects and birds are examples of invertebrates that have developed wings and muscles for flight. Burrowing: Many invertebrates, such as earthworms and moles, use their muscles to burrow into the ground.  VERTEBRATES MUSCLE SYSTEM Vertebrates, including humans, have intricate muscular systems that are far more complex than those found in invertebrates. Rather than simply being bundles of muscle fibers, vertebrate muscles are organized into groups that work together in a coordinated manner. These groups, or muscle compartments, are often separated by connective tissue sheaths, which help to organize and support the muscles.  VERTEBRATES MUSCLE SYSTEM Major Functions: Body movement and Maintenance of posture Respiration Production of body heat Communication Constriction of organs and vessels Heart beat VERTEBRATES MUSCLE SYSTEM Vertebrates have evolved specialized muscles for various functions, allowing them to perform a wide range of movements and maintain bodily functions. Skeletal Muscles Cardiac Muscles Smooth Muscles  VERTEBRATES MUSCLE SYSTEM Vertebrate muscular systems are highly efficient and allow us for coordinated precise movements. Nervous system control. The nervous system sends signals to muscles, coordinating their contractions and relaxations. This allows for complex movements, such as walking, running, and even playing musical instruments. Leverage system. Bones and joints act as levers, allowing muscles to generate force and produce movement. VERTEBRATES MUSCLE SYSTEM  VERTEBRATES MUSCLE SYSTEM Vertebrate muscular systems are highly efficient and allow for coordinated precise movements. Muscle attachments. Muscles are attached to bones at specific points, known as origins and insertions. This arrangement allows for a wide range of movements. Muscle fiber arrangement. The arrangement of muscle fibers within a muscle can influence its function. For example, muscles with parallel fibers are typically designed for strength, while muscles with pennate fibers are designed for speed and endurance.  VERTEBRATES MUSCLE SYSTEM Vertebrate muscular systems are highly efficient and allow for coordinated precise movements. Muscle attachments. Muscles are attached to bones at specific points, known as origins and insertions. This arrangement allows for a wide range of movements. Muscle fiber arrangement. The arrangement of muscle fibers within a muscle can influence its function. For example, muscles with parallel fibers are typically designed for strength, while muscles with pennate fibers are designed for speed and endurance.  TYPES OF MUSCLES The muscular system is a network of tissues that facilitates movement, maintains posture, and produces heat. It consists of separate muscles that contract to provide movement. Skeletal Muscles Cardiac Muscles Smooth Muscles  SKELETAL MUSCLES STRIATED or VOLUNTARY – this is under the control of the will and forms the large proportion of the body musculature; skeletal because, in most cases, it is attached to some part of the skeleton; striated because of the appearance of light and dark bands; cells are multinucleated; shape depends on its location and function SKELETAL MUSCLES Structure: Skeletal muscles, composed of elongated, multinucleated striations, are connected to bones via tendons. Control: They are voluntary Function: Plays a crucial role in body movements, maintaining posture, and producing heat during contraction. Examples: Biceps brachii, quadriceps, and pectoralis major. SKELETAL MUSCLES BICEPS BRACHII QUADRICEPS PECTORALS MAJOR  SMOOTH MUSCLES SMOOTH or NONSTRIATED or INVOLUNTARY – the movement is not under the control of the will but under the control of the sympathetic nervous system; Smooth muscle may also called involuntary muscle or visceral muscle. The cells of Smooth muscle have tapered ends, a single nucleus, and no striations. Although nerve impulses do bring about contractions, this is not something most of us can control, hence the name involuntary. The term visceral refers to internal organs, many of which contain smooth muscle.  SMOOTH MUSCLES Structure: Smooth muscles are spindle-shaped cells, single nucleus, and has no striations Control: They are involuntary Function: Plays a crucial role in body (e.g., contraction, peristalsis, blood vessel constriction, pupil dilation, urinary bladder emptying) Examples: Digestive tract, blood vessels, Respiratory system, urinary system, reproductive system, eye, etc. CARDIAC MUSCLE CARDIAC or STRIATED INVOLUNTARY MUSCLE - found only in the heart. It is striated yet involuntary. CARDIAC MUSCLE Cardiac muscle is the specialized muscular tissue that makes up the heart. It functions like a powerful pump, contracting rhythmically to circulate blood throughout the body. When it contracts, it squeezes blood from the heart's chambers and transports it to the lungs and body.  CARDIAC MUSCLE Structure: Cardiac muscle fibers are striated, branched, and interconnected by intercalated discs which facilitate synchronized contraction. They are usually mononucleated. Control: Involuntary control, regulated by the autonomic nervous system and hormones. Function: Pumps blood throughout the body by contracting the heart. Location: Found exclusively in the walls of the heart.  SMOOTH MUSCLES The functions of smooth muscle are actually functions of the organs in which the muscle is found. In the stomach and intestines, smooth muscle contracts in waves called peristalsis to propel food through the digestive tract.  SMOOTH MUSCLES Blood Vessels In the walls of arteries and veins, smooth muscle constricts or dilates the vessels to maintain normal blood pressure. The other blood vessels of great importance are the Arterioles. Arterioles are small arteries, and the smooth musclein their walls permits them to constrict (close) or dilate (open). SMOOTH MUSCLES Vascular Spasm After a blood vessel is severed, smooth muscle contracts (myogenic response) and platelets release serotonin, causing vasoconstriction to minimize bleeding. Labor Contractions Cervical stretching during labor sends signals to the hypothalamus, triggering oxytocin release, which stimulates strong uterine contractions for delivery. Pupil Regulation Smooth muscle fibers in the iris control pupil size, regulating light entry into the eye. Defecation Reflex Rectal stretching triggers sensory impulses to the spinal cord, leading to smooth muscle contraction, relaxation of the internal anal sphincter, and defecation. CORRELATION OF MUSCULAR SYSTEM STRUCTURES The muscular system's structures correlates with its functions mainly for protection, support, and movement in vertebrates. Protection: Skeletal muscles surround vital organs (e.g., heart, lungs) to shield them from injury. Smooth muscles in blood vessels regulate blood pressure and flow, protecting against damage. Muscular diaphragm separates chest and abdominal cavities, protecting organs. Support: Skeletal muscles maintain posture and stabilize joints. Smooth muscles in blood vessels support blood pressure and circulation. Muscular walls of hollow organs (e.g., digestive tract) provide structural integrity. Movement: Skeletal muscles contract to move bones and joints. Smooth muscles facilitate movement of substances through hollow organs (e.g., peristalsis). Cardiac muscle pumps blood throughout the body.  Aspect Invertebrates Vertebrates STRUCTURE Often has a hydrostatic skeleton Have an endoskeleton or exoskeleton Striated (skeletal and cardiac) and smooth Muscle fibers arranged in layers or bands muscle types No specialized muscle types Specialized muscles for different functions FUNCTION Generally provide flexibility and movement Enable precise and powerful movements Muscles can contract quickly and generate Muscles can work against fluid pressure more force Adapted for varied locomotion (e.g., crawling, Adapted for specific functions (e.g., flight, ADAPTATION swimming) running, swimming) May have specialized structures like tentacles or Advanced muscle control for complex siphons behaviors and activities  SIMILARITES AND DIFFERENCES Similarities: Differences: fundamental role of muscles in complexity of muscle structure movement and locomotion movements reliance on contractile proteins like muscles actin and myosin presence of nerve control for muscle contraction. both systems: adapt to their environments developing unique structures and functions suited to their lifestyles. Sliding Filament Theory  SLIDING FILAMENT THEORY The sliding filament theory explains the mechanism of muscle contraction based on actin and myosin filaments that slide past each other longitudinally producing more overlap between the thin and thick filaments. When the muscle contracts, sarcomeres become smaller. However the filaments do not change length.Instead they slide past each other Actin filaments slide between myosin filaments and the zone of overlap is larger. Each muscle cell has its own contractile apparatus Muscle fibers, or cells, consist of bundles of myofibrils. Myofibrils contain bundles of overlapping thick (myosin) and thin (actin) protein filaments. Sarcomeres (repeating groups of thick and thin filaments) are the contractile units (fundamental unit of muscle action)  Mechanism of filament sliding Myosin has structures called “myosin heads” , The myosin head binds a molecule of ATP. Myosin head is in its low- energy position. Myosin hydrolyzes the ATP to ADP and phosphate , releasing energy that extends the myosin head toward the thin filament. The myosin head extends further, and its other binding site latches on to the binding site of an actin. The result is a connection between the two filaments—a cross-bridge. ADP and P are released, and the myosin head pivots back to its low-energy configuration. This action, called the power stroke, pulls the thin filament toward the center of the sarcomere.  Mechanism of filament sliding Myosin has structures called “myosin heads” , The myosin head binds a molecule of ATP. Myosin head is in its low-energy position. Myosin hydrolyzes the ATP to ADP and phosphate , releasing energy that extends the myosin head toward the thin filament. The myosin head extends further, and its other binding site latches on to the binding site of an actin. The result is a connection between the two filaments—a cross-bridge. ADP and P are released, and the myosin head pivots back to its low-energy configuration. This action, called the power stroke, pulls the thin filament toward the center of the sarcomere. The cross-bridge remains intact until another ATP molecule binds to the myosin head, and cycle the repeats. Mechanism of filament sliding Diseases and Disorders Diseases and Disorders Muscular Dystrophy - inherited -is a group of diseases that cause progressive weakness and loss of muscle mass. -Duchenne MD -Becker MD -Common in boys  Diseases and Disorders Duchenne Muscular Dystrophy - a genetic disorder characterized by progressive muscle degeneration and weakness due to the alterations of a protein called dystrophin that helps keep muscle cells intact. Affects the Voluntary Movement of the body. Cause Due to the mutation in the gene responsible for producing dystrophin Diseases and Disorders SYMPTOMS No Cure Wheelchair Physical Therapy and Conditioning Scoliosis Glucocorticoids Treatment Dilated Cardiomyopathy Arrythmias  Diseases and Disorders Becker Muscular Dystrophy - is a genetic disease caused by a gene on the X chromosome Cause DMD and BMD is similar but they differ from one another. Diseases and Disorders SYMPTOMS No Cure Muscle Weakness Physical Therapy and Conditioning Difficulty Walking Muscle Biopsy Frequent Falls Have Trouble lifting heavy loads  Diseases and Disorders Myasthenia Gravis - a chronic autoimmune disorder in which antibodies destroy the communication between nerves and muscle, resulting in weakness of the skeletal muscles. CAUSE Mistakenly attacking its own healthy tissue, especially the Acetylcholine receptors at the Neuromuscular Junctions.  Diseases and Disorders Myasthenia Gravis - a chronic autoimmune disorder in which antibodies destroy the communication between nerves and muscle, resulting in weakness of the skeletal muscles. SYMPTOMS TREATMENT Drooping eyelid. Acetylcholinesterase Inhibitors Blurred or double vision. Slurred speech (Dysarthria) Immunosuppressive drug Problems chewing and swallowing. Surgery Removal of Thymus Weakness in the arms and legs. Chronic fatigue. Trouble breathing.  Diseases and Disorders Paralysis - a state of disablement, an inability to move. Anesthesia - without feeling or sensation